diff --git a/src/windows-emulator/memory_manager.cpp b/src/windows-emulator/memory_manager.cpp
index cabcd9f2..b5f6e574 100644
--- a/src/windows-emulator/memory_manager.cpp
+++ b/src/windows-emulator/memory_manager.cpp
@@ -504,7 +504,7 @@ uint64_t memory_manager::find_free_allocation_base(const size_t size, const uint
         start_address = align_up(region_end, ALLOCATION_GRANULARITY);
     }
 
-    if (start_address + size <= MAX_ALLOCATION_ADDRESS)
+    if (start_address + size <= MAX_ALLOCATION_END_EXCL)
     {
         return start_address;
     }
@@ -516,7 +516,7 @@ region_info memory_manager::get_region_info(const uint64_t address)
 {
     region_info result{};
     result.start = MIN_ALLOCATION_ADDRESS;
-    result.length = static_cast<size_t>(MAX_ALLOCATION_ADDRESS - result.start);
+    result.length = static_cast<size_t>(MAX_ALLOCATION_END_EXCL - result.start);
     result.permissions = nt_memory_permission();
     result.initial_permissions = nt_memory_permission();
     result.allocation_base = {};
@@ -541,7 +541,7 @@ region_info memory_manager::get_region_info(const uint64_t address)
     if (lower_end <= address)
     {
         result.start = lower_end;
-        result.length = static_cast<size_t>(MAX_ALLOCATION_ADDRESS - result.start);
+        result.length = static_cast<size_t>(MAX_ALLOCATION_END_EXCL - result.start);
         return result;
     }
 
diff --git a/src/windows-emulator/memory_manager.hpp b/src/windows-emulator/memory_manager.hpp
index 669d9ecc..a6467fee 100644
--- a/src/windows-emulator/memory_manager.hpp
+++ b/src/windows-emulator/memory_manager.hpp
@@ -12,6 +12,7 @@
 constexpr auto ALLOCATION_GRANULARITY = 0x0000000000010000ULL;
 constexpr auto MIN_ALLOCATION_ADDRESS = 0x0000000000010000ULL;
 constexpr auto MAX_ALLOCATION_ADDRESS = 0x00007ffffffeffffULL;
+constexpr auto MAX_ALLOCATION_END_EXCL = MAX_ALLOCATION_ADDRESS + 1ULL;
 
 // This maps to the `basic_memory_region` struct defined in
 // emulator\memory_region.hpp
diff --git a/src/windows-emulator/memory_utils.hpp b/src/windows-emulator/memory_utils.hpp
index 5c490223..632979c6 100644
--- a/src/windows-emulator/memory_utils.hpp
+++ b/src/windows-emulator/memory_utils.hpp
@@ -51,8 +51,10 @@ inline std::optional<nt_memory_permission> try_map_nt_to_emulator_protection(uin
     case PAGE_EXECUTE_READWRITE:
         common = memory_permission::all;
         break;
-    case 0:
     case PAGE_EXECUTE_WRITECOPY:
+        common = memory_permission::all;
+        break;
+    case 0:
     default:
         return std::nullopt;
     }
diff --git a/src/windows-emulator/syscalls/memory.cpp b/src/windows-emulator/syscalls/memory.cpp
index a727101c..0b8e45c3 100644
--- a/src/windows-emulator/syscalls/memory.cpp
+++ b/src/windows-emulator/syscalls/memory.cpp
@@ -20,6 +20,15 @@ namespace syscalls
             return STATUS_NOT_SUPPORTED;
         }
 
+        if (base_address < MIN_ALLOCATION_ADDRESS || base_address >= MAX_ALLOCATION_END_EXCL)
+        {
+            if (return_length)
+            {
+                return_length.write(0);
+            }
+            return STATUS_INVALID_PARAMETER;
+        }
+
         if (info_class == MemoryBasicInformation)
         {
             if (return_length)
diff --git a/src/windows-emulator/windows_emulator.cpp b/src/windows-emulator/windows_emulator.cpp
index ab9ecbd8..8cd1c0a8 100644
--- a/src/windows-emulator/windows_emulator.cpp
+++ b/src/windows-emulator/windows_emulator.cpp
@@ -443,8 +443,8 @@ void windows_emulator::setup_hooks()
         this->callbacks.on_rdtscp();
 
         const auto ticks = this->clock_->timestamp_counter();
-        this->emu().reg(x86_register::rax, ticks & 0xFFFFFFFF);
-        this->emu().reg(x86_register::rdx, (ticks >> 32) & 0xFFFFFFFF);
+        this->emu().reg(x86_register::rax, static_cast<uint32_t>(ticks));
+        this->emu().reg(x86_register::rdx, static_cast<uint32_t>(ticks >> 32));
 
         // Return the IA32_TSC_AUX value in RCX (low 32 bits)
         auto tsc_aux = 0; // Need to replace this with proper CPUID later
@@ -457,8 +457,8 @@ void windows_emulator::setup_hooks()
         this->callbacks.on_rdtsc();
 
         const auto ticks = this->clock_->timestamp_counter();
-        this->emu().reg(x86_register::rax, ticks & 0xFFFFFFFF);
-        this->emu().reg(x86_register::rdx, (ticks >> 32) & 0xFFFFFFFF);
+        this->emu().reg(x86_register::rax, static_cast<uint32_t>(ticks));
+        this->emu().reg(x86_register::rdx, static_cast<uint32_t>(ticks >> 32));
 
         return instruction_hook_continuation::skip_instruction;
     });